Hydrogenation process employing a transition metal catalyst



United States Patent 3,412,174 HYDROGENATION PROCESS EMPLOYING ATRANSITION METAL CATALYST Wolfram R. Kroll, Linden, N.J., assignor toEsso Research and Engineering Company, a corporation of Delaware NoDrawing. Continuation-impart of application Ser. No.

378,034, June 25, 1964. This application Aug. 19, 1966,

Ser. No. 573,497

36 Claims. (Cl. 260683.9)

ABSTRACT OF THE DISCLOSURE Active hydrogenation catalysts are preparedby the reaction of organoaluminum or organoaluminum monoalkoxidereducing agents with transition metal salts; the catalysts may befurther activated by the addition of Lewis bases, weak organic acids, oroxygen.

This application is a continuation-in-part of copending Ser. No. 378,034filed June 25, 1964, now abandoned, which in turn, is acontinuation-in-part of copending Ser. No. 281,347 filed May 17, 1963now US. Patent No. 3,323,902.

This invention relates to novel catalyst systems which have uitility ina number of environments, such as hydrogenation, hydroformylation,isomerization and electrochemical cells. More particularly, thisinvention relates to complex catalyst systems or Ziegler type catalystsand derivatives of such catalysts, all of which exhibit a high degree ofactivity in the above mentioned environments. In a preferred embodimentof this invention, the stability and/or activity of Ziegler typecatalysts is markedly improved by the addition of a third component,i.e. Lewis base, weak organic acid, oxygen, to the catalyst system.

Heterogeneous Ziegler type catalysts are well known in the art. US.Patent 2,781,410, for example, discloses a polymerization catalyst whichis composed of aluminum trialkyl and trace amounts of colloidal nickel.Despite exhaustive investigations, the potential usefulness of thesecatalyst systems for reactions other than polymerization anddisplacement has gone practically unnoticed until the present.

It has now been discovered that it is possible to employ modifiedZiegler type catalyst systems in such a manner that complex homogeneouscatalyst solutions, useful for hydrogenation of fatty acids forfoodstuffs, etc., can be prepared.

Thus, in accordance with this invention, a transition metal salt orcompound, or mixtures of such salts and/ or compounds, is reduced with aGroup III organometallic compound under conditions which favor theformation of a metal organic complex which contains the transition metalin a reduced valence state. Due to the nature of the various types ofreducing agents that are applicable to this invention, the use ofexcessive amounts of a particular reducing agent leads to a poisoning ofthe catalyst and consequent severe restriction of catalytic activity. Inan embodiment of this invention, however, poisoned catalyst systems maybe advantageously employed as selective hydrogenation catalysts. In apreferred embodiment of this invention, catalyst poisoning may beeliminated by the addition of a third component, i.e. Lewis base, weakorganic acid, oxygen, to catalyst systems which tend to become poisoned.In this latter embodiment, it has also been found that an enhancement ofcatalytic activity occurs in many instances.

3,412,174 Patented Nov. 19, 1968 ice The metal salts or compoundsreduced to form the catalyst system of the present invention aretransition metal salts or compounds. Thus, metals selected from each ofGroups I-B through VIII-B of the Periodic Chart of the Elements can besuccessfully employed. Preferred metals are those having an atomicnumber greater than 20 and less than 76. Some preferred metals are:titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copperwhich have an atomic number greater than 20 and less than 30, along withGroup VIII noble metals, e.g. platinum and rhenium. Particularlypreferred, however, are iron, cobalt, nickel which elements have anatomic number greater than 25 and less than 29, and platinum, whilenickel and cobalt, especially cobalt, are the most desirable.

The selection of the anionic component of the transition metal salt orcompound is not critical and both organic as well as inorganiccomponents may be employed. Typical examples of inorganic radicals thatmay be employed are halides, e.g. chloride, bromides, SiF cyanides,azides, etc. However, organic radicals, such as acetates andnaphthenates, are preferred anionic components because of theirexcellent solubility and drying characteristics. A particularlypreferred organic component is the chelate, e.g. the acetylacetonate,due to its excellent solubility and ready availability. Of course, otherchelates such as dimethylgloxime derivatives, tropolonates, orsalicyladehydes, etc. can also be utilized. Other organic componentsthat may be employed are the salts of organic acids, e.g. acetates,propionates, butyrates, valerates, etc. stearates, 'laurates, oleates,and other fatty acid salts, also salts of alcohols such as butanols,hexanols, octanols, glycols, eicosanols, cyclododecanol, etc. andalkoxides, e.g. ethoxides, benzoates, carbonates, acetylacetonates, andthe like. The transition metal compound can be a metal salt and may bedescribed as: a salt of an acidic organic compound in which the organicacid has a pKa in the range of 1-20; may be a carboxylic acid of pKaless than 9; from l-25 carbon atoms; from 12 acidic hydrogen atoms; andcontaining only carbon, hydrogen and oxygen; and can be monobasic with asolubility in benzene in parts per parts at 25 C. of at least 0.1 part.

The selection of a reducing agent is an important feature of thisinvention since it may alfect the activity of the catalyst system.Generally, Group I to Group III organometallic compounds can beemployed, e.g. aluminum, sodium, etc. However, organoaluminum ororganomagnesium compounds are preferred, particularly the organoaluminumcompounds. Thus, this invention will now be discussed with reference toorganoaluminum compounds, bearing in mind that the other organometallicswill operate similarly. The organoaluminum reducing agents can berepresented by the following formulae:

I. AlR OR II. AlR

wherein in Formula I R is a C -C hydrocarbyl radical, preferablyselected from the group consisting of C C alkyl, e.g. ethyl, propyl,isopropyl, butyl, isobutyl, pentyl, hexyl, heptyl, octyl, etc. bothisoand normal; cyclo'alkyl, e.g. cyclopentyl, cyclohexyl,cyclopentadienyl; aryl, e.g. phenyl, naphthyl; and alkaryl, e.g. benzyland is preferably C C hydrocarbyl and more preferably C -C alkyl. InFormula II R may be selected from the group consisting of hydrogen,halogen, and C -C hydrocarbyl and at least one R is hydrocarbyl, and thehydrocarbyl radicals are preferably as fully described above for FormulaI. Although these reducing agents can be used interchangeably in manyreactions, it is often preferable to employ the reducing agent shown inFormula I, hereinafter referred to as the monoalkoxide reducing agent.Typical examples of the reducing agents that may be employed are: (C HAlO(nC H Al(i-C H A1(C2H5)3, 3, A1(i-C4H9)2H, aluminum, trihexadecylaluminum, ethyl aluminum sesquichloride, etc.

The molar ratio of reducing agent to transistion metal salt is usuallyreported in terms of the molar ratio of aluminum to transition metal.Thus, regardless of the reducing agent employed, the molar ratio ofaluminum to transition metal should be at least 1/ 1, and usually anexcess is employed. Where the monoalkoxide reducing agent of Formula Iis employed, the molar ratio of aluminum to transition metal may rangeas high as 100/ 1, but is preferably about 5/1 to about 30/1. The use ofexcessive aluminum to transition metal molar ratios for the reducingagent of Formula II leads to poisoning of the catalyst system. Thus,when the AlR type reducing agent is employed the aluminum/transitionmetal molar ratio should be in the range of about 1/1 to 15/1,preferably 1/1 to 10/1 and more preferably l/1 to 4/1. By comparison,prior art, for example US. Patent 2,781,410, describes conventionalZiegler type catalysts which utilize only a trace amount of transitionmetal and have molar ratios as high as 5000/1. While no sufiicientexplanation is available, experimental data indicate that ratios inexcess of 10/1 tend to poison the catalyst and severely limit catalyticactivity (increasing molar ratios lead to increased poisoning).

While not wishing to be bound by any particular theory, it is believedthat the presence of excessive amounts of the AlR type reducing agentleads to further reaction of the reducing agent with the transitionmetal salt, i.e. alkylation and destruction of the chelate ligands wheresuch are employed, which in turn leads to a poisoned catalyst. Thispoisoning effect is not noticed when the monoalkoxide reducing agent isemployed, since it is believed that the AIR OR type reducing agent is aless strong alkylating agent than the AlR type. For this reason, the AlROR reducing agent is preferred.

In a preferred embodiment of this invention, a third component can beutilized to improve the stability and/ or enhance the catalytic activityof AlR type reducing agents. This third component, selected from thegroup consisting of Lewis bases, weak organic acids, and oxygen, whenadded in controlled amounts greatly enhances the AlR catalyst system.This result is particularly surprising since some of these compounds areknown to be catalyst poisons, i.e. oxygen is known to poison Raney typecatalysts. When the third component is employed, the molar ratio ofaluminum to transition metal may vary over a range similar to that forthe monoalkoxide reducing agent.

Thus, the complex catalyst systems of this invention may be morespecifically described as: (A) the reaction product of a transitionmetal salt and an organoaluminum compound of the formula AIR OR; (B) thereaction product of a transition metal salt and an organoaluminumcompound of the formula AlR and (C) the reaction product of a transitionmetal salt, an organoaluminum compound of the formula AlR and a thirdcomponent selected from the group consisting of Lewis bases, weakorganic acids and oxygen.

When the third component is utilized in the system denoted as (C) above,the improved activity and stability of the catalyst complex is believedto result from the conversion of free AlR into other species that are nolonger catalyst poisons.

Additionally, it is believed that some third components, i.e. Lewisbases and weak organic acids, participate in the formation of thecomplex catalyst either by supplying ligands for the reduced transitionmetal, i.e.

in the zero valence state, or by modifying the existing organometallicligands. While the addition of the third component will stabilize allAlR type catalyst sysytems, the Lewis bases and weak organic acids servedual functions: (1) to eliminate the poisoning effect of excessiveamounts of AIR;,, and (2) to react with the reduced transition metalcomplex catalyst by formation of new, superior complex catalyst systemswhich possess different properties, e.g. greater solubility, increasedthermal stability, and the like. The catalyst systems which areparticularly enhanced by Lewis bases and weak organic acids are thosewherein the transition metal is iron, cobalt, or nickel, particularlyiron or cobalt, and most particularly cobalt. The increased activity ofsuch systems is most notable when the anionic component of thetransition metal is a chelate, and most preferably when the chelate isthe acetylacetonate.

The amount of third component added depends on the amount of reducingagent utilized in preparing the catalyst system. Generally, enough thirdcomponent should be added so as to result in at least a stoichiometricratio of third component to reducing agent. It is normally preferred,however, to utilize a slight excess of third component, and molar ratiosof third component to organoaluminum reducing agent preferably rangefrom about 1/1 to 10/1, more preferably about 1/1 to 3/1. In cases wherethe third component is relatively expensive, only enough should beadded, i.e. at least stoichiometric ratios, to give the advantageousresults of this invention. Normally, the third component is added afterthe contacting of the organoaluminum compound and the transition metalsalt, except as noted hereinafter.

Of the third components that may be utilized in the process of thisinvention, Lewis bases make up a preferred class. Lewis bases aregenerally defined as substances that can furnish an electron pair toform a co-valent bond, i.e. an electron pair donor. Lewis bases are alsoexcellent solvents and/or co-solvents for preparing the catalyst and maybe used as such. Furthermore, Lewis bases impart an additional activityto the modified Ziegler type catalyst systems described herein. Thisincreased activity is particularly noticeable when cobalt compounds areemployed as the transition metal compound for preparing the solublecatalyst system. Preferred Lewis bases are the mono and (ii-functionalethers, e.g. dioxanes, tetrahydrofuran, 1,2-dimethoxyethane, anisole,diethylether, diisopropyl ether, diphenyl ether, methylethyl ether,diglyme, isopropylphenyl ether, etc. and tertiary amines, preferablyhaving 1 to about 10 carbon atoms, e.g. triethylamine, tripropylamine,tributyl amine and its homologous series, N-methyl morpholine,quinoline, tetrahydroquinoline, and the like; the ethers beingparticularly preferred.

It has also been discovered that, under the conditions of thisinvention, the Lewis base may be added to the organoaluminum reducingagent in at least a stoichiometric amount prior to the mixing of thereducing agent with the transition metal compound. This leads to theformation of a Lewis base-organoaluminum complex such as an etherate,which has different alkylation power than the AlR reducing agent andwhich is not a catalyst poison. Reductions using a Lewisbase-organoaluminum complex lead to catalysts with superior properties,e.g. higher hydrogenation activity. This effect upon catalyst activityin hydrogenations is quite surprising in view of some recently publishedliterature on Ziegler type catalysts which describes such procedures asbeing detrimental to the resulting polymerization system. However, notonly is this procedure not detrimental but it is also extremelyadvantageous in certain instances, e.g. the use of cobalt compounds tobe reduced by an etherate in the preparation of highly activehydrogenation catalysts.

Another type of third component which may be added advantageously to theZiegler type catalyst systems is a weak organic acid. Such materials aregenerally characterized as having weakly ionizable hydrogen atoms.Included among these are primary, secondary and tertiary alcohols andprimary and secondary amines having from about to about 20 carbon atoms,and preferably 1 to about carbon atoms. Particularly preferred compoundsare the tertiary alcohols in the above-mentioned carbon atom ranges,e.g. tert. butyl alcohol. Illustrative of the Weak acids that may beemployed are: methanol, hexanol, 2- ethyl hexanol, cyclohexanol, sec.butanol, n-butanol, octanol, cyclododecanol, glycols and the like.

The other type of third component that may be advantageously added tothe reduced metal catalyst systems is oxygen, as such, or as anoxygen-containing gas stream, e.g. nitrogen-oxygen, argon-oxygen, orother inert gasoxylgen streams. Preferred, however, is air because ofits ready availability.

The reduced metal catalyst system of the presentinvention can be easilyprepared by mixing the organoaluminum reducing agent with the transitionmetal compound, in molar ratios that are at least stoichiometric withrespect to aluminum and transition metal. The conditions of preparationare not critical and in most cases ambient conditions of temperaturesand pressures are quite satisfactory. However, reductions may be carriedout at temperatures in the range of about 60 C. to +150 C. preferably-10 to +100 C. Under circumstances where the transition metal compounddoes not instantaneously dissolve, the reduction may be accelerated,without dele terious effect, by employing temperatures in the upperportion of the above mentioned range.

The reduction, i.e. preparation of the catalyst, and subsequenthydrogenation is preferably carried out in the presence of an inertsolvent, although solvents are not essential to the success of thisinvention. Among the solvents are: aliphatics, aromatics, partiallyhydrogenated aromatics, ethers, tertiary amines, quinoline, partiallyhydrogenated quinolines, some alcohols, etc. Particularly preferredsolvents are C -C aliphatics, e.g. parafiins, such as pentane, heptane,octane, nonane, decane, and the like; C -C aromatics, e.g. benzene. Itshould be noted that benzene may be employed as a solvent only whensubsequent reaction conditions are such that the solvent will not behydrogenated.

It is quite interesting to note that catalyst systems of transitionmetal salts and AlR reducing agents, when poisoned to a limited extent,i.e. aluminum to transition metal molar ratios of 10/1 to 50/1,preferably 10/1 to 1, represent a highly useful technique for conductinghighly selective hydrogenation reactions. For example, the hydrogenationof an aliphatic side chain of an unsaturated cyclic compound, selectivehydrogenation of acetylenic impurities in olefinic compounds, etc. maybe effectively carried out with slightly poisoned catalysts.

The catalyst systems of the present invention may be utilized as highlyeffective hydrogenation catalysts. It has been discovered that thesecatalyst systems have superior activity when compared to commerciallyavailable Raney metal catalysts and exhibit this activity at unusuallylower temperatures and presure than are commonly employed. Thus, thecatalyst systems of the present invention may be successfully employedto reduce, generally, any unsaturated organic compound capable of beingreduced and preferably unsaturation in organic compounds possessingcarbon-carbon. carbonnitrogen and carbon-oxygen (as in carbonyl)unsaturation. Under certain conditions it can be used to hydrogenatecarbon to methane and nitrogen to ammonia.

Feeds containing carbon-carbon unsaturation may be unsubstituted orsubstituted with additional functional groups and include olefiniccompounds such as acyclic and cyclic mono-, diand triolefins, acetyleniccompounds and aromatic compounds. Typical examples of such compoundsare: butylenes, pentenes, hexenes, octenes, nonenes, cyclohexene,cyclopentadienes, cyclopentenes, cyclooctadiene, cyclododeoatrienes,cyclododecadiene, cyclododecene, vinyl cyclohexene, acetylene, hexyne-3,

octyne-3, phenyl acetylene, benzene, toluene, xylene, naphthalenes andthe like.

Feeds containing carbon-nitrogen unsaturation include nitriles, imines,oximes, heterocyclic nitrogen containing compounds, etc. Typicalexamples of such compounds are benzonitrile, benzylimine, quinoline,terephthalonitrile, isophthalonitrile, acetonitrile, propionitrile,tolunitrile, and the like.

Feeds containing carbonylic unsaturation include aldehydes, ketones andesters; typical examples of which are: acetone, methylethyl ketone,cyclohexanone, benzophenone, acetophenone, steroidal ketones, phorone,isophorone, benzaldehyde, acetaldehyde, propionaldehyde, propyl acetate,benzyl acetate, ethyl stearate, ethyl valerate and the like.

Since the hydrogenation reaction takes place with the feedstock in theliquid phase, any compounds falling within the definitions proposed forthe feeds, that are in the liquid phase at reaction conditions (andcapable of being reduced) may be utilized.

Hydrogenation reaction conditions may vary over wide limits dependingupon the particular feedstock to be hydrogenated. Normally,hydrogenation reactions may be carried out at temperatures ranging fromabout 20 C. to 500 C. preferably 20 to 250 C. and pressures in the rangeof about atmospheric to 15,000 p.s.i.g. of hydro gen, preferably atm. to3000 p.s.i.g. and more preferably 25 to 1000 p.s.i.g. Olefinicallyunsaturated materials are most preferably hydrogenated at temperaturesin the range of about 050 C. and pressures already indicated. When moredifficulty reducible feedstocks are employed, such as nitriles andaromatics, the reaction rate can be enhanced by higher temperatures andhydrogen pressures, e.g. up to about 500 C. and up to about 15,000p.s.i.g. may be employed.

The length of the hydrogenation reaction is not critical and reactiontimes ranging from 1 minute to 10 hours may be employed. Similarly, theconcentration of catalyst may vary over wide limits with only smallamounts being sufiicient to effect substantial conversions of thefeedstock. Ordinarily, 0.000l% to 1%, preferably 0.001 to 1% and morepreferably 0.01 to 0.1% of the transition metal based on feed to thereaction, may be employed.

In another embodiment of the present invention, it has been discoveredthat the catalyst system of this invention may be used advantageously toselectively hydrogenate certain types of unsaturation in preference toother types of unsaturation. The selective hydrogenation reactions whichmay be conducted include, for example, the hydrogenation of acetyleniccompounds present in small or trace amounts in a stream containing theseacetylenes and olefins; the hydrogenation of terminal olefinic bonds inpreference to internally bonded olefinic structures (this type ofselective reduction will take place even when both terminal and internalolefinic bonds exist in the same structure); the selective hydrogenationof aliphatic unsaturation in preference to the hydrogenation of anaromatic nucleus and the like. Generally, selective hydrogenations willbe governed by the type of catalyst and the appropriate solvent systememployed. Also, the choice of the stabilizing ligands complexed with theZero valent transition metal can enhance the selectivity of ahydrogenation catalyst.

Thus, selective hydrogenation reactions may be effected at moderatetemperatures and pressures, that is, at temperatures and pressures inthe lower part of the ranges previously mentioned.

Further, selective hydrogenations will normally be enhanced by employingcatalyst concentrations of a relatively low order. In addition, as abovementioned, catalyst systems of limited activity may be readily preparedusing the organoaluminum reducing agent in molar ratios of 10/ 1 to50/1, relative to transition metal. Thus, it can be easily seen thatthese selective hydrogenations are carried out at rather mild operatingconditions. More specifically,

selective hydrogenation reactions will normally occur at temperaturesbelow about 100 C., preferably below about 50 C. while pressures willusually be below about 100 atm., preferably below about 20 atm., morepreferably below about 10 atm., and catalyst concentrations below about1000 p.p.m. Some typical examples of the selective hydrogenationreactions that may be conducted are: reduction of aliphaticcarbon-carbon unsaturation at temperatures of about -100 C., hydrogenpressures of 1-10 atm., and catalyst concentrations of about -100p.p.m., e.g. vinylcyclohexene can be reduced to ethyl cyclohexene atabout C. and about 7 atm. hydrogen pressure; reduction of terminalolefinic bonds at temperatures of about 20 to +100 0, pressures of l20atm., and catalyst concentrations of about 10-1000 p.p.m. It should beremembered that conditions outside of these ranges may also be employed,depending upon the feedstock to the hydrogenation reaction. Thus, forexample, the reduction onf nitrile side chains on aromatic nuclei areusually effected at higher temperature and pressures. Some typicalexamples of the selective reactions that may be carried out are:vinylcyclohexene to ethylcyclohexene, cyclopentadiene to cyclopentene,cyclododecatriene to cyclododecadiene to cyclododecene, benzonitn'le tobenzylamine, benzophenone to diphenylmethane, etc.

The exact operating conditions under which selective hydrogenations maybe conducted will vary with the particular feedstock and type ofunsaturation involved. However, by following the general rulesheretofore set forth, a person ordinarily skilled in the art Will beable to determine the proper conditions for any selective hydrogenation.

This invention will now be further illustrated by the followingexamples. However, no limitations are to be inferred from these examplessince modifications will be obvious to those skilled in the art.

Example 1.-Comparison of Raney nickel catalysts v. reduced transitionmetal type catalysts Approximately 100-120 mg. of acetylacetonates ofiron, cobalt and nickel were weighed and charged to a reaction vessel.The respective salts were then reduced (as indicated in the table) witheither a solution containing 2 ml. triisobutylaluminum in 10 ml. ofheptane or 3 ml. of n-butoxy-aluminum diethyl in 10 ml. of heptane. Thereductions occur instantaneously and a homogeneous solution is obtained.In some cases a precipitate is observed which dissolves upon dilution.100 ml. of an 8% solution of cyclohexene in heptane was added to thecatalyst system and the mixture was hydrogenated at a constanttemperature of 22 C. and a constant pressure of 100 p.s.i.g. understirring. Samples were taken from time to time and analyzed by gaschromatography.

Similar hydrogenations were also carried out utilizing the same feed,solvent, temperature and pressure and a Raney nickel catalyst. Theresults are tabulated below:

The tabulated data indicate the much higher hydrogenation rate of thereduced catalysts compared with conventional Raney-nickel undercomparable conditions.

Example 2 In a procedure similar to Example 1 several transition metalsalts and chelates were reduced and screened for hydrogenation activity.The catalysts were prepared by treating approximately .4 mM. of thetransition metal compound with 4 mM. of the organoaluminum reducingagent in a heptane solvent. Hydrogenation conditions and 8 feeds similarto those employed in Example 1 were utilized. The results are tabulatedbelow:

TABLE II Transition Metal Reducing Agent in Catalyst Solvent Time for50% Conversion, min.

Following the procedures outlined in Examples 1 and 2 above, severalexperiments were carried out to determine the utility of other reducingagents and solvents in the complex catalytic system. The results aretabulated below:

TABLE III Transition Reducing Agent Solvent Time for 50% MetalConversion, min.

Co. Al(i-C4H9)3 Heptane 34 Co Al(i-C4H Dimethoxyethane 38 C0.Al(l-C4H0)3 Triethylamine 40 00.... Aid-0411mm... Benzene 30 00-...A1(C2H5)3 Hept-ane 31 C0 HA1(l-C9H9)-, .d0 33 The data indicate that awide variety of solvents and reducing agents may be used in the complexcatalyst system of this invention.

Example 4.-Comparison of AIR OR v. AlR reducing agents in catalystsystems for the hydrogenation of CDT and cyclohexene.

106.5 mg. cobalt-lI-acetylacetonate were reduced at room temperaturewith 1.6 g. (C H Al-O-nC H in 10 ml. of decane. Then 54 g.cyclododecatriene-cis-trans trans and 20 ml. decane were added undernitrogen. The reaction mixture was charged into an autoclave andhydrogenated at 1000 p.s.i. H and 55 C. After 44 minutes a sample wastaken and analyzed. It showed that conversion to cyclododecane hadoccurred.

In a similar experiment, .05 mM. cobalt-II-acetylacetonate were reducedwith 2 mM. (CH AlOC H in benzene, Al/Co ratio was 40/ 1. The catalystwas used for the hydrogenation of 100 mM. cyclohexene at 20 C. and 50p.s.i. H Within 2 hrs. 18.4% cyclohexane had formed.

In another similar experiment .05 mM. Cobalt-II- acetylacetonate werereduced with 2 mM. (CI-I Alacetylacetonate in benzene. The catalyst wasused for the hydrogenation of 100 mM. cyclohexene at 20 C. and 50 p.s.i.H Within 2 hrs. 7.1% cyclohexane had formed.

The above experiments clearly indicate that reducing agents having thegeneral formula AIR OR are desirable in the process of this invention.The Al/Co ratio was 40/1 in each of two foregoing illustrations.However, where the AlR system is employed, the catalyst is poisoned andcatalytic activity is severely limited.

Example 5.-Comparison of AlR v. etherate complex Soluble cobaltcatalysts were prepared by reaction of tri-isobutyl-aluminum with asolution of cobalt-II-acetylacetonate in benzene. This way severalcatalysts with a ratio A1:Co=4:1; 6:1; 8:1 and 10:1 were prepared.Another catalyst was prepared by reduction of the cobaltchelate with theetherate tri-isobutylaluminum-p-dioxane, using a ratio ofp-dioxane:Al:Co=10:8: 1. These catalysts were used in the hydrogenationof cyclohexene at 50 p.s i. H constant pressure and 20 C. constanttemperature. For each run 100 mM. cyclohexene and .1 mM. cobalt catalystwere taken, using 90 ml. benzene as solvent. The results are given inthe following table.

COMPARISON OF CATALYSTS PREPARED IN AND WITH- OUT PRESENCE OF A LEWISBASE Half-life Time for The results are indicative of the increasedcatalyst activity which may be obtained when a polar solvent such as anether is employed in the catalyst system and an etherate complex withthe organoaluminum compound is formed.

Example 6.Illustration of poisoning effect 110 mg. of cobaltacetylacetonate were reduced with 1.6 gm. of triethyl aluminum. Themolar ratio of Al/Co was approximately 35/ 1. A solution of cyclohexenewas added to the catalyst system and the mixture was hydrogenated at aconstant temperature of 22 C. and a constant pressure of 100 p.s.i.g.Analysis of the final product indicated that there was no conversion ofcyclohexene to cyclohexane. Similar results were obtained utilizingother trialkyl aluminum compounds as reducing agents and organoaluminummonochlorides.

The results indicate that the preferred conventional Zieglerpolymerization catalyst compositions do not exhibit effectivehydrogenation activity due to the critical nature of the Al/transitionmetal ratio.

Example 7 54 g. cyclododecatriene were hydrogenated at 50 C. and aconstant hydrogen pressure of 1000 p.s.i. The catalyst was prepared inthe following way: 143 mg. ferric-acetylacetonate were reduced with 2ml. triisobutylaluminum in ml. pentane. The reduction takes placeimmediately yielding a dark homogeneous product. To this is added theCDT and hydrogen pressured on. The reaction starts immediately which isnoticed by a temperature rise. Samples are taken in intervals andanalyzed by gas chromatography.

TABLE IV Weight Percent Time CDA 1 ODE 1 CDDE 3 CDT 4 (Min) 1Cyclododecane.

2 Cyclododeeene.

B Cyclododecadiene.

4 Cyelododecatriene. This example indicates that polyolefinic materialsmay be successfully hydrogenated by this invention.

Example 8.Hydrogenation of aromatics Example 9.Reduction ofcarbon-nitrogen bonds 250 mg. cobalt-acetylacetonate was reduced with 2ml. tri-isobutylaluminum to yield a homogeneous solution. To thecatalyst thus obtained 40 g. benzonitrile were 10 added and thehydrogenation performed at 1000 p.s.i. H and 150 C. Within 6 hours allnitrile was converted to the corresponding amine, i.e. benzylamine. Thisexample indicates that unsaturated nitrogen-carbon bonds may be reducedby the catalysts of this invention.

Example 10.Reduction of heterocyclic carbon-nitrogen bond A solublecobalt catalyst was prepared by reacting a solution of .4 mM.cobalt-II-acetylacetonate in benzene with a benzene solution containing4.0 mM. triisobutylaluminum and 5.0 mM. p-dioxane. Subsequently, 10.9 g.quinoline were added to the catalyst and then diluted to 50 ml. withp-xylene. The soluble mixture was changes to an autoclave andhydrogenated at 100 C., 1000 p.s.i. hydrogen pressure over 4 hours.After this time a sample was analyzed; it consisted of 11.3%

quinoline, 78.3% 1,2,3,4-tetrahydro-quinoline, 8.9%5,6,7,S-tetrahydro-quinoline, and 1.5% decahydroquinoline.

Example 11 Example l2.Selective hydrogenation at low temperature of apolyolefinic substance mg. nickel-acetylacetonate were reduced at 6 C.with a solution of 3 ml. tri-isobutylaluminum in 50 ml. pentane. Then 44g. cyclopentadiene monomer were added and the hydrogenation carried outat -6 C. and 1000 p.s.i. hydrogen presssure. Samples were withdrawn fromtime to time to evaluate the progress of the hydrogenation. Thefollowing table illustrates the selective hydrogenation achieved withthe complex catalyst system:

TABLE V Percent Percent Percent Time (minutes) CyclopentadieneCyclopentene Cyclopentane The results indicate that under controlledreaction conditions the catalyst systems of this invention may be madeeffective for highly selective hydrogenation.

Example 13.Hydrogenation of carbon-oxygen bond 250 mg. cobaltacetylacetonate were reacted with 4 ml. tri-isobutylaluminum in 10 ml.pentane. Then a solution of benzophenone (20 g.) in ml. ether was addedwhich had been dried with 2 ml. tri-isobutylaluminurn. The mixture washydrogenated at C. and 1500 p.s.i. for over 12 hours. Work-up of thereaction mixture and removal of solvents gave a product that consistedof 95% of diphenylmethane, 1% diphenylethane, the rest beingpolycondensated systems. No starting material was recovered. Thus thehydrogenation of the carbonyl compound to the hydrocarbon wasaccomplished indicating that unsaturated carbon-oxygen compounds may behydrogenated by the process of this invention.

Example 14.Selective hydrogenation of aliphatic olefinic bond 103 mg.cobalt-II-acetylacetonate in 6.8 g. diethylether are reduced with 1.6 g.tri-isobutylaluminum dissolved in 5 g. heptane. To this is added g.4-vinyl-cyclohexene-1 in 50 g. heptane solvent. The hydrogenation iscarried out at 22 C., 100 p.s.i. under stirring. After 10 minutes ofhydrogenation there is no more vinyl cyclohexene left, and 97%ethylcyclohexene and 3% ethylcyclohexane have been produced. Thus thehigh selectivity of this catalyst has been demonstrated.

Example .Selective hydrogenation of acetylenes 110 mg.cobalt-II-acetylacetonate were dissolved in 4.3 g. dimethoxy-ethane andreduced with 1.6 g. tri-isobutylaluminum in 5 g. heptane. To this wasadded .5 g. phenylacetylene and 53 g. of a heptane solution of hexene-l,containing 6.6 g. hexene-l. The solution was hydrogenated at 22 C. and100 p.s.i. hydrogen under stirring. The first sample after 10 minutesshowed no phenylacetylene whereas only a trace of the hexene-l washydrogenated and no hexene-l was isomerized. This example illustratesthat the novel catalyst system can be used with advantage to removetraces of acetylenic compounds from feedstreams containing olefinichydrocarbons.

Example 16.Activating effect of other Lewis bases (l620) A nickelcatalyst was prepared by reduction of .1 mm. nickel-II-acetylacetonatewith .8 mm. tri-isobutylaluminum in benzene. The catalyst gave ahalf-life of 96 minutes in the hydrogenation of cyclohexene at 22 C./150 p.s.i.

The same catalyst was prepared as above and 1.0 mm. p-dioxane was added.Subsequent hydrogenation of cyclohexene (standard conditions) gave ahalf-life of 41 minutes.

Example 17 Part A: A hydrogenation catalyst was prepared by reduction of.4 mm. cobalt-II-acetylacetonate with 4.0 mm. tri-isobutylaluminum in 98mm. cyclohexene. Hydrogenation at 22 C./100 p.s.i. gave 100% conversionin 203 minutes.

Part B: Subsequently a mixture of 8.0 cyclohexene (98 mm.) and 8.5 g.1,2 dimethoxyethane (106 mm.) was added to the autoclave containing thecatalyst and cyclohexane from previous run. Immediately after theaddition the hydrogenation was continued at 22 C. and 100 p.s.i. After58 minutes the hydrogenation was 100%.

Example 18 Cobalt-II-acetylacetonate (.4 mm.) is reduced with 4 mm.tri-isobutylaluminum in heptane. This is the same catalyst that was usedin Example 18, Part A. Cyclohexene (99 mm.) and 8.96 g. (88 mm.) ofN-methylmorpholine were added to the catalyst and a hydrogenation wascarried out under the same conditions as in Example 17. In 90 minutes100% conversion was obtained versus 203 minutes without the thirdcomponent.

Example 19 8.19 gms. of tri-isobutylaluminum (8 mm.) in a heptanesolution were added to 0.1145 gms. cobalt acetylacetonate (-26.2 mg.Co-0.4 mm.). The solution rapidly turned black with white fumes over theliquid. 5 minutes later 34.88 gms. of cyclohexene (96 mm.) were added tothe solution followed by 9.87 gms. Anisole (91 mm.). Hydrogenation at 22C./100 p.s.i.g. H gave 100% conversion in 155 minutes as compared to 203minutes without the ether in Example 17, Part A.

Example 20 In an experiment similar to Example 19, diphenyl ether (74mm.) was added to a similar solution of cyclohexene. Hydrogenation at 22C./100 p.s.i.g. H gave 100% conversion in 80 minutes, as compared to 203minutes without ether in Example 17, Part A.

Example 21.Use of weak organic acids as third components In this test aseries of various amounts of n-butanol are added as third components.Part A indicates the catalyst activity without third component. Part Bshows the improvement upon addition of 6.3 mm. n-butanol. Part C showsthat an excess of third component reduces the catalyst efliciencysomewhat, however, the catalyst in C is still more active than in A.

Part A: Cobalt-II-acetylacetonate (.4 mm.) was reduced withtriethylaluminum ,7.5 mm.) in heptane. The catalyst thus obtained wasused in a cyclohexene hydrogenation at 22 C. and 100 p.s.i. It was verypoor (2% in 2 hours).

Part B: Again .4 mm. cobalt-H-acetylacetonate was reduced withtriethylaluminum (8.1 mm.) in heptane and then reacted 6.3 mm. n-butanolin heptane. The catalyst was immediately used for the standardhydrogenation of 99 mm. cyclohexene (same conditions as in Part A)giving a half-life time of 38 minutes.

Part C: Here .4 mm. cobalt-H-acetylacetonate was reduced with 7.9 mm.tri-isobutylaluminum in heptane and subsequently reacted with 26.5 mm.n-butanol. Immediately the catalyst was used for a standard cyclohexene(97 mm.) hydrogenation at 22 C. and 100 p.s.i. The catalyst gave 22%conversion in 4 hours.

Example 22 This example shows the effect of a preferred third componentof the class of weak organic acids: t-butyl alcohol. It is assumed thatthe alcohol reacts with formation of a t-butoxy derivative of thecatalyst. This new catalyst formed is superior in promoting etfect,selectivity and handling. The following table shows that an excess oftbutyl alcohol does not reduce catalyst efiiciency.

TABLE VI [mM. =mil1imo1e] 1 In the hydrogenation of oyclohexene.

Example 23.--Use of air to effect catalyst efliciency In this example ameasured amount of air was used to stabilize the catalyst and increasehydrogenation activity.

Part A: Cobalt-ILacetylacetonate 102 mg.) were reduced with 2 ml.tri-isobutylaluminum. The resulting catalyst was used for thehydrogenation of cyclododecatriene (CDT) (54 g.) at around 55 C. and1000 p.s.i. In 138 minutes only 11.8% cyclododecane was produced.

Part B: Similarly 103.7 mg. cobalt-II-acetylactonate was reduced with 2ml. tri-isobutylaluminum in decane and 54 g. CDT were added.Subsequently, 49 ml. oxygen were added to the system (as air) understirring. Then the hydrogenation was carried out at 53 C. and 1000p.s.i. After 135 minutes the conversion to cyclododecane was Example 24The superiority of AlR OR as reducing agent over AlR is demonstrated forthe selective hydrogenation of cyclooctadiene-l,5: catalyst A wasprepared by reduction of 114 mg. cobalt-II-acetylacetonate with 3 ml.diethylaluminum-n-butoxide, whereas catalyst B was prepared by reductionof 111 mg. cobalt-II-acetylacetonate with 3 ml. tri-isobutylaluminum. Ineach hydrogenation 36 g. COD (cyclooctadiene-1,5) plus 40 ml. heptanewere used. Each hydrogenation was carried out at ambient temperature and-980-1000 p.s.i. constant pressure.

13 14 TABLE VII 3. The process of claim 1 wherein the transition metalsalt is a chelate. Catalyst Tune (mm') i i a a? 4. The process of claim1 wherein the molar ratio of aluminum to transition metal is about /1 to30/1. ii 3 3;} 5 5. The process of claim 1 wherein the unsaturatedcompound contains carbon-carbon unsaturation. COD=Cyclooctad1ene.COE=Cyclooctene. COA=Cyelooctane. 6. A process for reducing unsaturatedorganic Example 25 pounds having unsaturated sites selected from thegroup Cobalt-II-acetylacetonate (104 mg.) was reduced with consisting ofCfIFbOIPQaYbOH, f f and 4 diethy1a1u.mihum n hutoxide and Subsequentlyused 10 bonyl unsaturationwhrch comprises reacting the unsatufor thehydrogenation of octyne 4 At 995 Psi and rated compound with hydrogen attemperatures of about 56 C., after 70 minutes 97% selectivity towardsoctenes +2500 and f f' Presslues of about at 100% conversion wasOhtaihed mospheric to about 3000 p.s.1.g. 1n the presence of a catalystconsisting essentially of the reaction product of a Example 26LWPressure hydrogeuauou transition metal salt, an organoalurninum compoundof cyclohexaue 0 having the formula A1R wherein R is selected from theCobalt-II-acetylacetonate (.1 mm.) was reduced with g p Consisting of yg halogen, and 2- 2o ytri-isobutylaluminum (.6 mm.) and the catalystused to drocarbyl rad s and at least one R is y hX and hydrogenatecyclohexene (150 mm.) at 25 p.s.i. and a third c mp Selected from thegroup cohslstlng of A h lfllif f 2 mil-L was b i d, 20 Lewls bases, weakorganic acids, and oxygen, the molar ratio of third component toaluminum being about 1/1 to Example 27 10/1, and the molar ratioaluminum to transition metal A reduced nickel catalyst was prepared from540 mg. is at least l/l. nickel-II-acetylacetonate and 10.8 g. of anequimolar mix- 7. The process of claim 6 wherein the third componentture of diethylaluminum chloride and ethyl aluminum diis a Lewis base.chloride (ethyl aluminum sesquichloride). A portion of 8. The process ofclaim 7 wherein the transition metal this catalyst was used tohydrogenate 80 g. of dicyclois selected from the group consisting ofiron, cobalt, and pentadiene at ambient temperature and 1000/1700 p.s.i.nickel. Analysis indicated that the product consisted of 73% 9. Theprocess of claim 7 wherein the transition metal dihydro and 27%tetrahydro derivatives. 30 salt is cobalt acetylacetonate.

Example 28 anlghghe process of claim 7 wherein the Lewis base is Thefollowing table lists other unsaturated hydrocar- 11. The process ofclaim 10 wherein the catalyst conbons that can be successfullyhydrogenated utilizing the sists essentially of a homogeneous solutionof a transiprocess of this invention. tion metal salt and an etherate,the etherate being a com- TABLE VIII Compound Product Conv. Temp., 0.Press, Trans percent p.s.i. Metal Norbornene 99+ Ambient.... 1,400 NiHeXene-l HeXane 93+ .-do 250 F9 Cyclooctad1ene 100 30 1 1,000 Go3-methylbuten 91.5 Ambient... 990 Fe 2-methylbutene-2 2-methylbutane-..23 50 990 Co In each case the acetylacetonate of each transition metalplex derived from the r tion an aluminum trialkyl, was reduced withtri-isobutylaluminum. each alkyl of which contains 2-20 carbon atoms,and an ether. Examp 1e 29 12. The process of claim 6 wherein theunsaturated h examplfi hemohstratesfhe feaslhlhty of a 1 compound is anolefin and the temperature is about 0 duction of two differenttransition metal chelates which to 50 C and the pressure is about 25 to110 psig 15 0f afivahtagfi 1n the Prepafahoh of m temperature 13. Theprocess of claim 6 wherein the third compoand POISOII resistantcatalysts. nent is aweak organic acid.

mixture of Cobalt-u-acetylacetonate g) and 14. The process of claim 13wherein the weak organic nickel-TLacetylacetonate (51.6 mg.) werereduced in hepi i a CF02) alcohoL tane with tri-lsobutylaluminum (1.6g.). The co-reduced 55 15 The process f claim 3 wherein the weak organiccatalyst was successfully used in the hydrogenation of idi tertiarybutyl 1 1 cyffloheXene at (1 and 100 P- After 133 16. The process ofclaim 6 wherein the third compomm 87% of the cyclohexene had beenhydrogenated. m i Oxygen.

What 15 clalmed 1S3 17. A process for reducing unsaturated organic com-A PTOFeSS for reducmg unsaturated orgaulu pounds having unsaturatedsites selected from the group pounds having unsaturated sites selectedfrom the group consisting of carbon-carbon, carbon-nitrogen, and cargg sa fi g iigg f ifiii gghzigztgtfifgihsi g :3: bonyl unsaturation whichcomprises reacting the unsaturated compound with hydrogen attemperatures of about g s, mp 2 g, 2 hydiogen at temperatures of about-20 to +250 C. and hydrogen pressures of about ato ydrogen Pressure ofabout 25 mospheric to about 3000 p.s.i.g. in the presence of a cataf 'ito 9 m the Presence of a catalyst i lyst consisting essentially of thereaction product of a sistlng essentrallyof the reaction product of atransltron transition metal Salt and an organoaluminum compound metalsalt, wherein the transition metal 1s selected from having the formulaAIRZOR wherein R is a crczo the group consisting of Iron, cobalt, andnickel, an ordrocarbyl radical and the molar ratio of aluminum toganoalumihum compound of the formula s WhereiIlR transition metal is atleast 1/1, and in the presence of an is Selected from the groupconsisting of y g inert Solvent gen, and C -C hydrocarbyl and at leastone R is hydro- 2. The process of claim 1 wherein the transition metalcarbyl, and an ether, the molar ratio of ether to alumiis selected fromthe group consisting of iron, cobalt, and nurn being about 1/1 to 10/1and the molar ratio of nickel. aluminum to transition metal is at least1/ 1.

18. The process of claim 17 wherein the reaction is carried out in thepresence of a solvent selected from the group consisting ofhydrocarbons, ethers, amines, and alcohols.

19. The process of claim 17 wherein the unsaturation is carbon-carbon.

20. The process of claim 17 wherein the transition metal salt is cobaltacetylacetonate.

21. A process for preparing a hydrogenation catalyst which consistsessentially of reacting a transition metal salt, an organoaluminumcompound of the formula AlR wherein R is selected from the groupconsisting of hydrogen, halogen, C -C hydrocarbyl radicals and at leastone R is hydrocarbyl, and a third component selected from the groupconsisting of Lewis bases and weak organic acids, at temperatures ofabout 60 to +150 (3., the molar ratio of third component to aluminumbeing about 1/1 to 10/1, and the molar ratio of aluminum to transitionmetal is at least 1/1, thereby forming a reaction product containing thetransition metal which is in a reduced valence state.

22. The process of claim 21 wherein the third component is a Lewis base.

23. The product of claim 22.

24. The process of claim 21 wherein the third component is a weakorganic acid.

25. The process of claim 24 wherein the weak organic acid is a tertiaryalcohol.

26. The product of claim 25.

27. Method for the preparation of a complex hydrogenation catalyst whichcomprises reacting in an inert liquid hydrocarbon diluent at atemperature in the range from about 60 C. to +150 C., compoundsconsisting essentially of (a) one formula weight of a metal salt of anacidic organic compound, said metal having an atomic number greater than25 and less than 29, and said organic acid having a pKa in the rangefrom about 1-20, from 1-25 carbon atoms, from 1-2 acidic hydrogen atoms,and only carbon, hydrogen, and oxygen; and

(b) from 1-10 moles of a Mendeleyev Periodic Table Group IIIorganometallic compound, MR in which 16 M is a Group III element and Ris selected from the radical groups consisting of hydrocarbyl andhydrogen, said hydrocarbyl radicals having from l20 carbon atoms pergroup, and wherein at least one radical group of said compound ishydrocarbyl.

28. The meihod of claim 27, wherein said reacting is in the absence of asolvent.

29. The method of claim 27, wherein aluminum is the metal component.

30. The method of claim 29, wherein for each formula weight of saidmetal salt, 1 to 4 moles of said organometallic compound is used in thereacting.

31. The method of claim 30, wherein said organic acid is mono basic,having a solubility in benzene in parts per parts at 25 C. of at least0.1 part.

32. The method of claim 31 wherein said organic acid is carboxylic,having a pKa less than 9.

33. The composition of claim 32.

34. Method of decreasing the unsaturation of a reducible organiccompound which comprises contacting said compound in the liquid phasewith hydrogen in the presence of about 0.0011.0 formula percent of acomplex hydrogenation catalyst prepared as in claim 27, said contactingbeing at a temperature in the range 20 to 500 C. at a hydrogen pressureof from atmospheric to 15,000 p.s.i.g. and for a period of from about 1minute to 10 hours, and recovering the resulting hydrogenated organiccompound.

35. The method of claim 33 wherein said catalyst is prepared as in claim32, and said reducible compound is an unsaturated hydrocarbon.

36. The method of claim 34 wherein said reducible hydrocarbon is acyclic hydrocarbon.

References Cited v UNITED STATES PATENTS 3,113,986 12/1963 Breslow etal. 260667' 3,205,278 9/1965 Lapporte 260-667 3,247,270 4/1966 Kirk252-428 3,281,375 10/1966 Vandenberg 252429 DELBERT E. GANTZ, PrimaryExaminer.

